Small Gods is occasionally mentioned in some of the Discworld reading order flowcharts as an entry point for new readers, but definitely not in all of them. Personally, I think it's a quite solid entry point into the world for the following reasons. For one thing, it's the third (publication order) standalone novel. The first one is Pyramids and the second one is Moving Pictures. Thematically, Moving Pictures is often considered as the first Industrial Revolution themed novel set in the Discworld, so if one is interested in tracking progress in the Discworld towards (a parody of) modern times, Moving Pictures is a sensible starting point for that.
However, both Pyramids and Small Gods explore (parodied) ancient civilizations. In my opinion, based on a just finished reread of Small Gods and a fairly recent reread of Pyramids, Small Gods is a significantly stronger standalone novel than Pyramids which would serve as an excellent entry point into the Discworld for adults who want to get a sense of what all the enthusiasm for the Discworld is about.
Many of the earlier (by publication date) entry points into the Discworld (e.g. The Colour of Magic, Sourcery, Equal Rites, perhaps even Pyramids) are somewhat less strong for adult readers than Small Gods as a first choice for a Discworld read.
If an adult reader wants to sample Pratchett's Discworld without committing to a series which follows one or more main characters over time, Small Gods is a great choice for a first Discworld read.
by MiddletownBooks